Air-compressor.



UNITED STATES PATENT OFFICE..

- y EBENEZER HILL, OF sOUTH NORWALK, CONNECTICUT.

AIRFCOMPRESSOR.

SPECIFICATION forming part of Letters Patent N0. 688,520, dated December 10, 1901. `Applicationtiled October 9, 1901. Serial No.' 78,051. (No model.)

To all whom it may con/cern: Y

Be it known that I, EBENEZER HILL, a citi'- zen of 4vthe United States, residing at South Norwalk, in the county'ot Fairield and State of Connecticut, have linvented certain new and usefullmprovementsin Air-Compressors, oi which the following is a speciication.

Thisinvention relates to a multiple-stage `compressor which is so built that air may be drawn off at different pressures coincidently without Vinterference-for instance, at low pressure for operating a mine-pump, when necessary, aud simultaneously at high pressure for driving mine-locomotives, as desired.

The object is to'so construct a compressor that air may be drawn from an intercooler or pipe connecting two cylinders ata predetermined pressure for any length of time without any practicalpreduction of pressure in the capacity of the momentary discharge `through the outlet from the interduct and having a valvethat is opened and closed for establishing"` or shutting oft communication between the auxiliary reservoir and the higher-pressure,cylinder as the low-pressure air is used or shut oft.

In the accompanying drawings the invention is represented as embodied in a two-stage compressor. t

Figure 1 is an elevation, with parts cut inA section, of the air-cylinders of such a compressor; and Fig.r 2 isa view, on larger scale, of a portion of an auxiliary reservoir, showing its Valve and connection with rthehighpressure cylinder. j v p The double-acting lowpressurekairLcylinder 1 has at each end common inlet-valves 2 I and outlet-Valves 3. The double-acting highpressure air'cylinder 4:" ateach end has common inlet-valves 5 and outletsvalves 6. The

low and high pressure cylinders are connect'- ed by an ordinary intercooler 7. lThis intercooler has anoutlet-pipe 8, through which air at low pressure may be drawn when the valve 9 is open. l

In a pocket 10 in the head 1l at each end of the high-pressure cylinder is an inwardlyopening Valve 12 with a stem 13, that is mov'- ably supported by a frame 14, held in the head by a plug 15. l A threaded Aspindle 16 tlirns in a threaded socket in the plug, with its inner end adjacent to the endof the valves'tem. The spindle has a handle 17,by which it may be turned, so as to engage the stem and hold the valve open. A passage 18 leads from each pocket to a pipe 19, that is connected with the upper end of an auxiliary reservoir 20. These reservoirs are designed to be of such size thatthey will hold substantially the saine quantity of air as isdrawn from the intercooler for low-pressure use during each pulsation of the pistons. When the valve 9 in the outlet 8, through which the lowpressure air may be drawn from the intercooler, is shut, air is drawn in, compressed in the rst cylinder, cooled in the intercooler, compressed in the second cylinder, and discharged to the high pressure receiver as usual, the inlet and outlet Valves of the high and low pressure cylinders operating in the ordinary manner and the valves 12 remaining closed. When the valve 9 is open, air may be drawn off for use at the pressure in the intercooler. If nothing else is done, as

the second cylinder is' designed to receive just so much air the withdrawal of air from the intercooler will lessen the'volume of air for the second cylinder, and thus cause a fall of pressure in the intercooler and a reduction of the action of the second piston. v However,

with this machine when the Valve 9 is open to draw off air at low pressure the valves 12 are held open, so as to establish communication between the highpressure cylinder and the auxiliary reservoirs. As the air in the auxiliary reservoirs is substantially "equal to the quantity of air that is momentarily drawn from the intercooler, when the high-pressure piston moves back and forth and lair rushes in from the intercooler the quantity that is drawn oft for low-pressure use is supplied by the quantity in the auxiliary reservoirsM-that IOO is, the air in these reservoirs when the valves l2 are held open pulsates in and out and occupies the space of the air drawn 0H, so that the volume of air in the high-pressure cylinder remains the same as if none were drawn off from the intercooler. These auxiliary reservoirs can be connected with the higher pressure of any two cylinders of a multiplestage compressor from between which air is drawn for lowpressure use, and of course they can be used at either or both ends of the highpressure cylinder. By means of this arrangement of auxiliary reservoirs air can be drawn o at low pressure from any interd uct of a multiplehstage compressor Without reduction of pressure in them and without lessening the Volume of air in the high-pressure cylinder, so that the high-pressure cylinder' will operate normally.

l. A compound air-compressor having cylinders, pistons, inlet-Valves,dischargeyalves, interduct between the cylinders, an outlet from the interduct, an auxiliary reservoir connected with the high-pressure cylinder of the pair that are connected by the interduct that is tapped, and a valve controlling the passage from the high-pressure cylinder to the auxiliary reservoir, substantially as specified.

2. A compound air-compressor having cylinders, pistons-,inlet-valves,discharge-valves, interduct between the cylinders, an outlet from the interduct, an auxiliary reservoir connected with each end of the high-pressure cylinder of the pair that are connected by the interduct that is tapped, and a valve controlling each passage from the high-pressure cylinder to cach auxiliary reservoir, substan-4 tially as specified.

3. A-compoundair-compressor having cylinders, pistons,inlet-valves,discharge-valves, interduct between the cylinders, an outlet from the interduct, an auxiliary reservoir connected with the high-pressure cylinder of the pair that are connected by the interduct that is tapped, a valve controlling the passage from the high-pressure cylinder to the auxil# iary reservoir, and means for holding the aux# iliary-reservoir valve open, substantially as specified.

4. A compound air-compressor having cyl-v inders, pistons,inletvalves, discharge-Valves, interduct between the cylinders, an outlet from the interduct, a pocket in the head of the high-pressure cylinder ofthe pair thatare connected by the interduct that is tapped, an inwardlyopening valve located inl said pocket, means for holding the valve open, and an auxiliary reservoir connected with the pocket, substantially as specified.

5. In combination with a multiple-stage air'- compressor having an interduct that is tapped for drawing air at low pressure, an auxiliary reservoir having a capacity for air substantially equal to the quantity of air that is withdrawn from the interduct for low-'pressure use at each pulsation of the pistons, and a connection from the auxiliary reservoir to the highpressure cylinder of the pair that the tappedinterduct connects, substantially as specified.

EBENEZER HILL. Witnesses:

J. E. SLATER, L. O. DOWNS 

